Automated guided vehicles (AGVs) are battery-powered, self-driven vehicles used to transport material and other items from one location to another without any accompanying operator. AGVs are being increasingly used in the material handling industry and are an important part of the shift in production planning from a primary emphasis on high-speed production to also focus on efficient transportation of materials between work stations as well as into and out of storage. AGVs are important in this regard since they are capable of responding to changing transport patterns and can be integrated into modern manufacturing plants, where flexible material handling systems are now required to perform an efficient routing of materials.
Traditional AGV Systems include several common elements. The first of these is a central computer or server that acts as a dispatcher for all AGVs. This AGV central server contains software that provides several functions for the successful operation of an AGV System, as follows:                Traffic Control—Manages the movement of AGVs throughout a facility. This includes sending messages to the AGVs that they are allowed to move a certain distance along a predetermined guide path. All AGVs are simultaneously controlled in this manner so that they do not collide with one another.        Facility Interface—Communicates directly to facility, plant, or warehouse control software. In this manner, the movement of material/products/inventory is coordinated such that the objectives of the facility are met. Communications also occur with facility equipment that the AGVs must service. These communication links are typically accomplished over a facility LAN to a computer server or to programmable logic controllers (PLCs).        Inventory Management—Many AGV systems require the management of facility inventory in a warehouse or similar area. The AGV central server understands the physical layout of the facility and controls the storage and retrieval of product in inventory areas to achieve facility objectives. Some facilities have their own inventory management system, and in these cases the AGV central server functions to move loads as instructed by the high level controller of the facility management system. In most cases, AGVs will receive information about the load they are carrying and pass this information to the AGV central server when the load is delivered.        Order Control—This function creates orders to move materials or inventory in the facility. Orders consist of a pick and then a drop of a load. These orders are then assigned to the AGVs based on a series of rules to optimize overall throughput and utilization of the AGV system. Factors taken into consideration include, for example, the proximity of an AGV to the pick location of an order, battery level of the AGV, assigning an order to the correct type of AGV if they are multiple styles in a system, and meeting specific objectives such as response time to start the order.        Communications—This function manages data communications between all elements of the AGV System. These elements include the AGVs, facility computers and PLCs, battery charging systems, battery exchange locations, automatic doors, elevators, etc. Communications to the AGVs is accomplished over a wireless network which typically already exists in the customer's facility or is provided by the customer as part of the installation of the AGV Systems.        Battery Level Management—This function monitors the battery level of all AGVs and instructs the AGVs to either travel to a location to have the battery automatically or manually exchanged, or to a location where the AGVs automatically connect to a charger when time permits.        Data Management—The AGV central computer is a clearinghouse for all AGV system operational information and therefore is required to process a tremendous amount of data. This data is managed and reports or alerts are generated to assess the current status and performance of the AGV system along with numerous system metrics.        
The AGVs in a typical AGV system act like soldiers that take commands from the AGV central server and execute those orders. The AGVs are provided with information about the entire guide/travel path and contain routines that are executed along the guide path as they journey from one location to another. The AGVs execute routines for load picks and drops, but the AGVs do not execute any commands unless instructed by the AGV central server. In addition, the AGVs do not keep track of the work functions they perform, do not manage inventory, and do not retain data about the load they are carrying. This is all accomplished by the AGV central server.
In complex AGV Systems where there are many pick and drop locations, there are also many inventory management and logistics rules. As such, the AGV central server is essential to management of the entire AGV System within the facility. However, in order to successfully implement an AGV system with an AGV central server and to operate such, significant technical resources from the customer are required. Also, a very significant investment must be made in not only the required equipment, but also the programing of the AGV central server and the installation of the AGV system.
Not all material handling situations require, or can justify the cost of, a traditional AGV system with its central computer or server to operate and control the AGVs, especially if the number of AGVs required is modest; for example, in the range of 1-5 vehicles. There is a need for an efficient and reliable AGV system to focus on the routine automated movement of materials in manufacturing plants and warehouses in a decentralized manner, without the necessity of a computer implemented central server or host.